1. Field of the Invention
The present invention relates to a magnetic head actuator having a finely movable tracking device and, more particularly, to a power feeding structure for wiring to a piezoelectric element of the tracking device.
2. Description of the Related Art
A magnetic head actuator widely used in an HDD is provided with a magnetic head opposing a rotating hard disk. The magnetic head is positioned at the free end of a swing arm, which swings reciprocally around the rotation axis of the base of the swing arm. In accordance with tracking signals from the hard disk, the actuator allows the swing arm to swing around the rotation axis. In order to meet the demand for a narrower track width or a smaller track pitch, a finely movable tracking device is constructed, such that a piezoelectric element, which expands and contracts when a voltage is applied, is mounted in the swing arm. Thus, the free end of the swing arm makes a fine arcuate movement around the rotation axis of the arm in accordance with expansion and contraction of the piezoelectric element.
In a conventional magnetic head actuator provided with the finely movable tracking device, a ground electrode of the piezoelectric element is electrically connected to the swing arm, and power is supplied to a voltage-impressing electrode via a feeding line of a flexible printed circuit (FPC) board that extends along the swing arm. The feeding line of the FPC board and the voltage-impressing electrode of the piezoelectric element are bonded by conventional gold (Au) wire bonding.
The Au wire bonding, however, is not only expensive due to the many man-hours required but also the Au wire bond is easily broken by an external force applied to the thin Au wire, which has a diameter on the order of a few micrometers. Also, a component, such as a magnetic head actuator that is incorporated into an HDD in an additional step after assembly the wiring is easily broken, thereby leading to continuity defects and low yield.